Any device creating motion in a straight line is a linear actuator. A vehicle is an excellent example of linear motion—the engine makes the car move forward or back in a straight line, unless the driver changes the direction. Other examples of this application are available in the process industries, material handling, food, and beverages processing industry, robotics, and many more.
The industry uses different types of linear actuators powered by pneumatics, hydraulic, and/or electric. As it is natural for pneumatic and hydraulic power to produce linear motion, they are simple devices and the industry often calls them cylinders. On the other hand, electric powered linear actuators almost always use a rotary electric motor. That means converting the rotary motion to a linear one through a belt or a screw/nut system. Although conversion does make the electric linear actuator somewhat more complex than pneumatic or hydraulic actuators are, using electricity can offer significant advantages in several applications.
Engineers must make a crucial decision when selecting the type of linear actuator they prefer for use in a specific application. For instance, although the pneumatic cylinder offers the advantages of lower cost and ease of use, the user often confronts potential compressed air leaks that reduce the efficiencies in operation. Similarly, although providing high-thrust capabilities, a hydraulic cylinder is prone to fluid leaks and they may not be very friendly to the environment.
On the other hand, electric linear actuators offer distinct benefits:
- Ability to handle complex motion profiles
- Ability to adapt quickly to changing needs
- High efficiency, lower energy usage, and lower lifetime costs
- Integrates easily into other electric production systems
With motion-control systems becoming increasingly more complicated, electric linear actuators provide precise control of force, deceleration, acceleration, and speed. Their ease of use allows them to outperform easily other technologies dependent on fluid power. Easily handling complex motion profiles, electric linear actuators offer infinite positioning capabilities with data feedback and high accuracy and repeatability.
It is easy to change the programming of an electric actuator. As parameters change, changing the program allows the actuator to adjust to the new specifications. Not only does this minimize downtime, it also reduces loss of productivity in the industry.
Compared to the 10-15% total system efficiency for pneumatic systems and 40-50% for hydraulic systems, electric powered linear actuators operate at 70-80%. Although the initial acquisition cost may be high, electricity powered linear actuators offer savings over their lower total life cycle cost, apart from the savings in energy use, efficiency, and reduced maintenance.
If all other equipment in the system operate on electricity, it is easy for users to integrate electric actuators also into the motion control system. Users can take advantage of integrating electric actuators in systems that use PLCs, HMIs and other similar devices for enhancing motion control, data collection, and diagnostics.
In the market, numerous actuator types/styles are available and they come in various degrees of precision and cost. For instance, one can have models that offer high repeatability, but with moderate accuracy. It is necessary to understand the requirements in the application for selecting a suitable actuator.